1. Field of the Invention
The present invention relates to an optical disk device that reads data recorded in a CD, DVD or other such optical disk, and records data to such optical disk. The present invention also relates to a track-on method of a pickup of such optical disk device.
2. Background Information
Optical disk devices that read data recorded in a CD, DVD or other such optical disks and record data to such optical disk have become hugely popular. As shown in Japanese Patent Application Publications Nos. 2002-93081 and 2000-11393, such optical disk devices are equipped with a pickup head. Such pickup head reads data recorded in an optical disk by directing a laser beam at an optical disk that is mounted in a main unit of the optical disk device, and detecting the light reflected by the optical disk.
The pickup head is provided with a laser diode (LD) that functions as the light source, an objective lens for focusing the laser beam outputted from the LD onto the recording surface of the optical disk, a photodiode (PD) that receives the light reflected from the optical disk, a biaxial actuator that moves the objective lens toward and away from the optical disk and in the radial direction of the optical disk, and so forth. The pickup head is supported so as to be movable in the radial direction of the optical disk.
Beside the pickup head, the optical disk device is further equipped with a thread motor for moving the pickup head in the radial direction of the optical disk, and a drive IC for supplying drive voltage to the thread motor. This drive IC supplies the thread motor with drive voltage as directed by a controller. The thread motor is driven by the drive voltage supplied from the drive IC. The pickup head is moved in the radial direction of the optical disk by the drive force of the thread motor.
With an optical disk device, the position (recording track) in an optical disk at which data to be read are recorded is controlled by moving the pickup head in the radial direction of the optical disk with a thread motor, and by to moving the objective lens in the radial direction of the optical disk with an actuator.
However, the drive voltage actually supplied to the thread motor can vary from the voltage specified by the controller. This is due to a variance in the amplification factors of the drive voltages of the drive ICs that supply drive voltage to the thread motor of the optical disk device.
With an optical disk device, when the power is first switched on or when an optical disk is mounted, an operation of moving the pickup head to the innermost peripheral position and then toward the outer periphery by a predetermined amount to the track-on position of the optical disk (hereinafter, this operation will be referred to as “re-zeroing”) is performed. A problem is that the above-mentioned variance in amplification factors among the drive ICs results in variance in the track-on position at which the pickup head is positioned at the end of the re-zeroing (this position will hereinafter be referred to as the re-zeroing position) among different optical disk devices.
Consequently, depending on the optical disk, it is sometimes impossible to move the pickup head to a proper zeroing position in a single re-zeroing operation. When such problem is encountered conventionally, a retry operation is performed, in which the drive voltage used in the re-zeroing is changed. Although it is possible to start tracking at the proper re-zeroing position by changing the drive voltage, but this retry operation takes extra time.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved optical disk device and a track-on method of such optical disk device that overcome the problems of the conventional art. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.